UPDATE-CA-TRUST(8) UPDATE-CA-TRUST(8)
NAME
update-ca-trust - manage consolidated and dynamic configuration of CA
certificates and associated trust
SYNOPSIS
update-ca-trust [COMMAND]
DESCRIPTION
update-ca-trust(8) is used to manage a consolidated and dynamic
configuration feature of Certificate Authority (CA) certificates and
associated trust.
The feature is available for new applications that read the
consolidated configuration files found in the
/etc/pki/ca-trust/extracted directory or that load the PKCS#11 module
p11-kit-trust.so
Parts of the new feature are also provided in a way to make it useful
for legacy applications.
Many legacy applications expect CA certificates and trust configuration
in a fixed location, contained in files with particular path and name,
or by referring to a classic PKCS#11 trust module provided by the NSS
cryptographic library.
The dynamic configuration feature provides functionally compatible
replacements for classic configuration files and for the classic NSS
trust module named libnssckbi.
In order to enable legacy applications, that read the classic files or
access the classic module, to make use of the new consolidated and
dynamic configuration feature, the classic filenames have been changed
to symbolic links. The symbolic links refer to dynamically created and
consolidated output stored below the /etc/pki/ca-trust/extracted
directory hierarchy.
The output is produced using the update-ca-trust command (without
parameters), or using the update-ca-trust extract command. In order to
produce the output, a flexible set of source configuration is read, as
described in section SOURCE CONFIGURATION.
In addition, the classic PKCS#11 module is replaced with a new PKCS#11
module (p11-kit-trust.so) that dynamically reads the same source
configuration.
SOURCE CONFIGURATION
The dynamic configuration feature uses several source directories that
will be scanned for any number of source files. It is important to
select the correct subdirectory for adding files, as the subdirectory
defines how contained certificates will be trusted or distrusted, and
which file formats are read.
Files in subdirectories below the directory hierarchy
/usr/share/pki/ca-trust-source/ contain CA certificates and trust
settings in the PEM file format. The trust settings found here will be
interpreted with a low priority.
Files in subdirectories below the directory hierarchy
/etc/pki/ca-trust/source/ contain CA certificates and trust settings in
the PEM file format. The trust settings found here will be interpreted
with a high priority.
You may use the following rules of thumb to decide, whether your
configuration files should be added to the /etc or rather to the /usr
directory hierarchy:
o If you are manually adding a configuration file to a system, you
probably want it to override any other default configuration, and
you most likely should add it to the respective subdirectory in the
/etc hierarchy.
o If you are creating a package that provides additional root CA
certificates, that is intended for distribution to several computer
systems, but you still want to allow the administrator to override
your list, then your package should add your files to the
respective subdirectory in the /usr hierarchy.
o If you are creating a package that is supposed to override the
default system trust settings, that is intended for distribution to
several computer systems, then your package should install the
files to the respective subdirectory in the /etc hierarchy.
QUICK HELP 1: To add a certificate in the simple PEM or DER file
formats to the list of CAs trusted on the system:
o add it as a new file to directory /etc/pki/ca-trust/source/anchors/
o run update-ca-trust extract
QUICK HELP 2: If your certificate is in the extended BEGIN TRUSTED file
format (which may contain distrust/blacklist trust flags, or trust
flags for usages other than TLS) then:
o add it as a new file to directory /etc/pki/ca-trust/source/
o run update-ca-trust extract
In order to offer simplicity and flexibility, the way certificate files
are treated depends on the subdirectory they are installed to.
o simple trust anchors subdirectory:
/usr/share/pki/ca-trust-source/anchors/ or
/etc/pki/ca-trust/source/anchors/
o simple blacklist (distrust) subdirectory:
/usr/share/pki/ca-trust-source/blacklist/ or
/etc/pki/ca-trust/source/blacklist/
o extended format directory: /usr/share/pki/ca-trust-source/ or
/etc/pki/ca-trust/source/
In the main directories /usr/share/pki/ca-trust-source/ or
/etc/pki/ca-trust/source/ you may install one or multiple files in the
following file formats:
o certificate files that include trust flags, in the BEGIN/END
TRUSTED CERTIFICATE file format (any file name), which have been
created using the openssl x509 tool and the -addreject -addtrust
options. Bundle files with multiple certificates are supported.
o files in the p11-kit file format using the .p11-kit file name
extension, which can (e.g.) be used to distrust certificates based
on serial number and issuer name, without having the full
certificate available. (This is currently an undocumented format,
to be extended later. For examples of the supported formats, see
the files shipped with the ca-certificates package.)
o certificate files without trust flags in either the DER file format
or in the PEM (BEGIN/END CERTIFICATE) file format (any file name).
Such files will be added with neutral trust, neither trusted nor
distrusted. They will simply be known to the system, which might be
helpful to assist cryptographic software in constructing chains of
certificates. (If you want a CA certificate in these file formats
to be trusted, you should remove it from this directory and move it
to the ./anchors subdirectory instead.)
In the anchors subdirectories /usr/share/pki/ca-trust-source/anchors/
or /etc/pki/ca-trust/source/anchors/ you may install one or multiple
certificates in either the DER file format or in the PEM (BEGIN/END
CERTIFICATE) file format. Each certificate will be treated as trusted
for all purposes.
In the blacklist subdirectories
/usr/share/pki/ca-trust-source/blacklist/ or
/etc/pki/ca-trust/source/blacklist/ you may install one or multiple
certificates in either the DER file format or in the PEM (BEGIN/END
CERTIFICATE) file format. Each certificate will be treated as
distrusted for all purposes.
Please refer to the x509(1) manual page for the documentation of the
BEGIN/END CERTIFICATE and BEGIN/END TRUSTED CERTIFICATE file formats.
Applications that rely on a static file for a list of trusted CAs may
load one of the files found in the /etc/pki/ca-trust/extracted
directory. After modifying any file in the
/usr/share/pki/ca-trust-source/ or /etc/pki/ca-trust/source/
directories or in any of their subdirectories, or after adding a file,
it is necessary to run the update-ca-trust extract command, in order to
update the consolidated files in /etc/pki/ca-trust/extracted/ .
Applications that load the classic PKCS#11 module using filename
libnssckbi.so (which has been converted into a symbolic link pointing
to the new module) and any application capable of loading PKCS#11
modules and loading p11-kit-trust.so, will benefit from the dynamically
merged set of certificates and trust information stored in the
/usr/share/pki/ca-trust-source/ and /etc/pki/ca-trust/source/
directories.
EXTRACTED CONFIGURATION
The directory /etc/pki/ca-trust/extracted/ contains generated CA
certificate bundle files which are created and updated, based on the
SOURCE CONFIGURATION by running the update-ca-trust extract command.
If your application isn't able to load the PKCS#11 module
p11-kit-trust.so, then you can use these files in your application to
load a list of global root CA certificates.
Please never manually edit the files stored in this directory, because
your changes will be lost and the files automatically overwritten, each
time the update-ca-trust extract command gets executed.
In order to install new trusted or distrusted certificates, please
rather install them in the respective subdirectory below the
/usr/share/pki/ca-trust-source/ or /etc/pki/ca-trust/source/
directories, as described in the SOURCE CONFIGURATION section.
The directory /etc/pki/ca-trust/extracted/java/ contains a CA
certificate bundle in the java keystore file format. Distrust
information cannot be represented in this file format, and distrusted
certificates are missing from these files. File cacerts contains CA
certificates trusted for TLS server authentication.
The directory /etc/pki/ca-trust/extracted/openssl/ contains CA
certificate bundle files in the extended BEGIN/END TRUSTED CERTIFICATE
file format, as described in the x509(1) manual page. File
ca-bundle.trust.crt contains the full set of all trusted or distrusted
certificates, including the associated trust flags.
The directory /etc/pki/ca-trust/extracted/pem/ contains CA certificate
bundle files in the simple BEGIN/END CERTIFICATE file format, as
described in the x509(1) manual page. Distrust information cannot be
represented in this file format, and distrusted certificates are
missing from these files. File tls-ca-bundle.pem contains CA
certificates trusted for TLS server authentication. File
email-ca-bundle.pem contains CA certificates trusted for E-Mail
protection. File objsign-ca-bundle.pem contains CA certificates trusted
for code signing.
The directory /etc/pki/ca-trust/extracted/edk2/ contains a CA
certificate bundle ("cacerts.bin") in the "sequence of
EFI_SIGNATURE_LISTs" format, defined in the UEFI-2.7 specification,
sections "31.4.1 Signature Database" and "EFI_CERT_X509_GUID". Distrust
information cannot be represented in this file format, and distrusted
certificates are missing from these files. File "cacerts.bin" contains
CA certificates trusted for TLS server authentication.
COMMANDS
(absent/empty command)
Same as the extract command described below. (However, the command
may print fewer warnings, as this command is being run during rpm
package installation, where non-fatal status output is undesired.)
extract
Instruct update-ca-trust to scan the SOURCE CONFIGURATION and
produce updated versions of the consolidated configuration files
stored below the /etc/pki/ca-trust/extracted directory hierarchy.
FILES
/etc/pki/tls/certs/ca-bundle.crt
Classic filename, file contains a list of CA certificates trusted
for TLS server authentication usage, in the simple BEGIN/END
CERTIFICATE file format, without distrust information. This file is
a symbolic link that refers to the consolidated output created by
the update-ca-trust command.
/etc/pki/tls/certs/ca-bundle.trust.crt
Classic filename, file contains a list of CA certificates in the
extended BEGIN/END TRUSTED CERTIFICATE file format, which includes
trust (and/or distrust) flags specific to certificate usage. This
file is a symbolic link that refers to the consolidated output
created by the update-ca-trust command.
/etc/pki/java/cacerts
Classic filename, file contains a list of CA certificates trusted
for TLS server authentication usage, in the Java keystore file
format, without distrust information. This file is a symbolic link
that refers to the consolidated output created by the
update-ca-trust command.
/usr/share/pki/ca-trust-source
Contains multiple, low priority source configuration files as
explained in section SOURCE CONFIGURATION. Please pay attention to
the specific meanings of the respective subdirectories.
/etc/pki/ca-trust/source
Contains multiple, high priority source configuration files as
explained in section SOURCE CONFIGURATION. Please pay attention to
the specific meanings of the respective subdirectories.
/etc/pki/ca-trust/extracted
Contains consolidated and automatically generated configuration
files for consumption by applications, which are created using the
update-ca-trust extract command. Don't edit files in this
directory, because they will be overwritten. See section EXTRACTED
CONFIGURATION for additional details.
AUTHOR
Written by Kai Engert and Stef Walter.
update-ca-trust 08/21/2024 UPDATE-CA-TRUST(8)
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